Agreement between a radiologist and an otolaryngologist in adenoid-to-nasopharyngeal ratio measurement on lateral cephalometric radiographs and its association with tympanometric findings in children undergoing adenoidectomy

Aims: Adenoid hypertrophy is a common pediatric condition associated with Eustachian tube dysfunction and middle ear disease. Although the adenoid-to-nasopharyngeal (A/N) ratio is widely used for radiographic assessment of adenoid size, its reproducibility between observers from different clinical disciplines and its association with middle ear dysfunction remain uncertain. This study aimed to evaluate the agreement between a radiologist and an otolaryngologist in A/N ratio measurement and the association between the A/N ratio and tympanometric findings in children undergoing adenoidectomy. Methods: This retrospective study included 171 pediatric patients who underwent adenoidectomy and had preoperative lateral cephalometric radiographs and tympanometric examinations. A/N ratios were independently measured by one radiologist and one otolaryngologist. Agreement was assessed using the intraclass correlation coefficient (ICC), Bland-Altman analysis with formal testing for proportional bias, and Cohen’s kappa after dichotomisation at published thresholds. Associations between the A/N ratio and tympanometric patterns were evaluated using nonparametric tests, receiver operating characteristic (ROC) analysis, and multivariable logistic regression. Results: Agreement between the two observers was good [ICC=0.796, 95% confidence interval (CI): 0.73-0.85; p<0.001]. The mean interobserver difference was 0.007±0.064, with 95% limits of agreement of -0.119 to 0.134 and no significant proportional bias (p=0.098). At a threshold of 0.73, the observers agreed in 89.5% of cases (κ=0.683), although 10.5% of children were classified differently. A/N ratios did not differ significantly among tympanometric groups, and ROC analysis demonstrated poor discrimination for pathological tympanometric findings (area under the curve 0.545-0.562). In multivariable logistic regression, age was independently associated with pathological tympanometric findings (OR 0.82 per year, 95% CI: 0.71-0.95, p=0.007), whereas the A/N ratio was not (p=0.389). Technical factors did not significantly influence the magnitude of interobserver disagreement. Conclusion: The A/N ratio is a reproducible radiographic parameter with good agreement between the two participating observers, but it shows limited value as a standalone discriminator of middle ear dysfunction in children selected for adenoidectomy. Patient age may represent a more clinically relevant determinant of tympanometric status than radiographic adenoid size alone.